# leetcode\_165

## Compare two version numbers version1 and version2.

If version1 > version2 return 1; if version1 < version2 return -1;otherwise return 0.

You may assume that the version strings are non-empty and contain only digits and the . character.

The . character does not represent a decimal point and is used to separate number sequences.

For instance, 2.5 is not "two and a half" or "half way to version three", it is the fifth second-level revision of the second first-level revision.

You may assume the default revision number for each level of a version number to be 0. For example, version number 3.4 has a revision number of 3 and 4 for its first and second level revision number. Its third and fourth level revision number are both 0.

```
Example 1:

Input: version1 = "0.1", version2 = "1.1"
Output: -1
Example 2:

Input: version1 = "1.0.1", version2 = "1"
Output: 1
Example 3:

Input: version1 = "7.5.2.4", version2 = "7.5.3"
Output: -1
Example 4:

Input: version1 = "1.01", version2 = "1.001"
Output: 0
Explanation: Ignoring leading zeroes, both “01” and “001" represent the same number “1”
Example 5:

Input: version1 = "1.0", version2 = "1.0.0"
Output: 0
Explanation: The first version number does not have a third level revision number, which means its third level revision number is default to "0"
```

## Note:

Version strings are composed of numeric strings separated by dots . and this numeric strings may have leading zeroes. Version strings do not start or end with dots, and they will not be two consecutive dots.

## Solutions

1. **straight forward**
2. watch out cases when:
   * `1.2.0` and `1.2.0.0.0.00`.
   * `1.2.01` and `1.2.00001`.

```python
class Solution:
    def compareVersion(self, version1: str, version2: str) -> int:
        ss1, ss2 = ([int(i) for i in v.split('.')]
                    for v in (version1, version2))
        d = len(ss1) - len(ss2)
        # fill with 0 to keep the same length
        ss1, ss2 = ss1 + [0] * -d, ss2 + [0] * d
        return (ss1 > ss2) - (ss2 > ss1)
```

```cpp
class Solution {
public:
    vector<int> split(const string & s, char delimiter = '.') {
        vector<int> tokens;
        string token;
        istringstream tokenstream(s);
        while (getline(tokenstream, token, delimiter))
            tokens.push_back(stoi(token));
        return tokens;
    }
    int compareVersion(string version1, string version2) {
        auto s1 = split(version1);
        auto s2 = split(version2);
        if (s1.size() < s2.size()) s1.resize(s2.size());
        else s2.resize(s1.size());
        int i = 0;
        while (i < s1.size() && s1[i] == s2[i])
            i++;
        return s1.size() == i ? 0 : (s1[i] > s2[i] ? 1 : -1);

    }
};
```